1. Field of the Invention
The present invention relates, in general, to novel multidirectional fiber arrays and, in particular, to unidirectional arrays of graphite, glass or other fibers interconnected with polymer fibers. The invention further involves a process of preparing the multidirectional fiber arrays by the mechanical agitation of the unidirectional arrays in cooling polymer solutions. In addition, the invention is directed to composites of these multidirectional arrays in solid polymeric matrices.
2. Description of the Prior Art
Known fiber/resin composites are fabricated by resin impregnation of unidirectional or crosswoven arrays of graphite, glass or other fibers. The inherent weakness of such composites is that while the fibers provide reinforcement in their axial directions, there is no reinforcement in the transverse direction, between fibers and between laminations.
U.S. Pat. No. 4,127,624 to Keller et al, the disclosure of which is incorporated herein by reference, is directed to forming new random three-dimensional polymeric fiber masses by mechanical agitation of cooling polymer solutions under controlled conditions. No suggestion was made in Keller et al, however, for utilizing their technique of precipitating the polymer in three dimensional, interconnected networks of high strength fibers to interconnect and reinforce larger unidirectionally strung graphite, glass and other fibers or to possibly reinforce the interlaminar region between layers of such larger fibers.
Production of two- or three-dimensional arrays in which graphite, glass or other fibers provide strength in one direction while interconnected polymer fibers provide it in the other(s), as well as fabrication of composites of these materials impregnated with resin, have, heretofore, been impossible.
The present invention advantageously provides novel multidirectional fiber arrays comprising unidirectional or cross-woven arrays of graphite, glass or other fibers interconnected with polymer fibers, as well as a process for preparing said novel fiber arrays.
This invention advantageously also provides novel unidirectional fiber/resin/polymer composites.
This invention advantageously further provides multidirectional fiber arrays and fiber/resin composites which are reinforced in both the axial and transverse directions.
This invention advantageously still further provides fiber arrays wherein microscopic polymer fibers of high strength and elongation are deposited to interconnect, larger, unidirectionally strung fibers.